RO/DI phosphates & silicates

[discuspro]

I have a RO/DI system that is producing water with roughly a 0 TDS reading. Is it possible that phosphates and/or silicates are still going into my system from the RO/DI?

[NaCl_H2O]

At 0 TDS I would think that would mean nothing but H2O! However, how confident are you in your TDS meter?

[discuspro]

Yup pretty confident, calibrated and tests correctly against calibration solution. The reason I'm asking is the continual search of mine to find the source of nutrients or other junk feeding my cyanobacteria that is going crazy!

The way I think of it, a TDS meter measures ions/charged particles that can conduct an electrical charge. Non-ionized molecules like non-polar organics (some protiens), I would think, would go undetected because they have little or no polarity the convey the charge a TDS meter is sending. I don't know :wacko

[GaryP]

Stuff like organics shouldn't get through the carbon filter. In addition, it would never make it through the RO membrane. They are way to big for that.

[demodiki]

I had some cyano and so I purchased a RO/DI unit. The cyano persisted for a couple of months but after weekly water changes has finally disappeared. Your system may just need time to purge what is in the rocks/sand, etc. Also, keep an eye on what you are feeding.

A phosphate sponge or polyfilter may help get that little bit out.

Anyways, that is what has worked for me.